Somewhere deep in the woods is a creature who always remains unseen and to help him achieve that his farts needs to smell like the surrounding natural environment that he lives in.
Bigfoots fart smells like the forest, very outdoorsy, so he can blend in and remain unnoticed and unseen while leaving no trace of his existence.
To be exact, Bigfoots farts smell like sandalwood & cedar wood.
Even Bigfoot needs to pass gas every now and then.
